The objective of the investigation was to compare the degree of interobserver agreement in determining the histological grade of uterine endometrial endometrioid adenocarcinoma using the criteria proposed by the three-grade FIGO classification (1988) and the new, two-grade system proposed by Lax et al. (2000). In the FIGO system, the assessment is focused on the amount of solid, non-squamous growth pattern and the additional feature is the presence of the so-called "notable nuclear atypia" (nuclear grade), with the latter criterion not having been precisely defined. In the two-grade system, the evaluation concentrates on the amount of the solid component, regardless of its character, type of neoplastic growth pattern (expansive or diffusely infiltrating) and the presence of necrosis within the tumor mass. A total of 133 cases of uterine endometrial carcinoma were evaluated, determining the stage according to the FIGO classification and assessing the histological grade based on the criteria presented by the above two systems. All the cases were separately examined by 5 pathologists with varying degrees of experience in gynecological pathology. A higher degree of interobserver agreement was demonstrated when the two-grade system was employed as compared to the FIGO system, regardless whether the material was evaluated by experienced pathologists (FIGO k - 0.64 - 0.71, binary - 0.91 - 0.92), or by individuals with little experience in gynecological pathology (FIGO k - 0.23 - 0.48, binary - 0.21 - 0.57). The data point to the superior character of the two-grade system as to the agreement of the histological grade assessment, but also suggest a considerable effect of experience on the precision of the evaluation.